Preparation of fire-extinguishing material comprising heating biuret with sodium or potassium hydroxide

ABSTRACT

Fire-extinguishing compositions containing the compound having the empirical formula MC2N2H3O3 where M represents sodium or potassium, are made by heating biuret with sodium hydroxide or potassium hydroxide under anhydrous conditions.

United States Patent [151 3,642,621

Hollows 1 Feb. 15, 1972 [541 PREPARATION or FIRE- [56] References cm EXTINGUISHING MATERIAL COMPRISING HEATING BIURET WITH UNHED STATES PATENTS- I 3,150,177 9/1964 Kluge SODIUM 0R POTASSIUM HYDROXIDE 3,484,372 12/1969 Birchall 72 Inventor: Frank Brian Hollows, Northwich, England 3,536,620 10/1970 Birchall $25212 [731. Assignee: Imperial Chemical Industries Limited,

London, England Filed: Feb. 1969 Primary Examiner-John T. Goolkasian Assistant Examiner-D. J. Fritsch.

[21] APPL 7 156 Attorney'Cushman, Darby & Cushman 30 F A h P" 57 ABSTRACT fi D ta orelgn ca on onty a Fire-extinguishing compositions containing the compound Feb. 16, 1968 Great Britain ..7,768/68 having the empirical formula MC N H O where M represents sodium or potassium, are made by heating biuret with sodium [52] U.S.Cl ..252/5, 106/ 15, 1 17/137, hydroxide or potassium hydroxide under anhydrous condi- 252/2, 252/4, 260/553 tions. [51] Int. Cl. ..A62d 1/00 m [58] Fieldof "25 2/2, 7; 117/137; 106/15 F13; 260/553 B 3 Claims, No

PREPARATION OF FIRE-EXTINGUISHING MATERIAL COMPRISING HEATING BIURET WITH SODIUM R POTASSIUM HYDROXIDE This invention relates to a novel process for making a fireextinguishing material having the ability to extinguish flames arising from the combustion of liquid and gaseous fuels such as liquid hydrocarbons, hydrogen, methane and of solid fuels such as wood, paper and textiles.

In U.S. application Ser. No. 676,907 now US. Pat. 3,536,620 we have described novel compounds for use in extinguishing fires having the empirical formula MC,N H O where M represents an atom of sodium or potassium, and made by heating a mixture of urea and at least one alkali selected from bicarbonates, carbonates, sesquicarbonates and hydroxides of sodium and potassium at temperatures below 150 C.

We have now found that these compounds MC N H O can be made by reactions between sodium or potassium hydroxides and biuret under anhydrous conditions.

The products of the reactions are mixtures of the compounds MC N l-l o and hydroxides and carbonates of sodium or potassium. They possess fire-extinguishing properties owing principally to the MC N l-l O in them but the alkali hydroxides and carbonates also contribute to the total effect.

The invention thus provides a process for making compositions having fire-extinguishing properties comprising heating biuret with sodium hydroxide or potassium hydroxide in the absence of water.

in one method of carrying out the process the alkali metal hydroxide and the biuret are mixed in powdered form and heated under anhydrous conditions for several hours at a temperature from 100 C. to 130 C.

In another method the alkali metal hydroxide and biuret are heated together in an inert, nonaqueous, liquid reaction medium, for example toluene, xylene and other organic solvents that permit heating or refluxing at temperatures above about 95 C. under atmospheric pressure. The metal hydroxide can conveniently be dissolved in methanol or ethanol and the solution added to a suspension of biuret in, for example, toluene and the mixture heated until all the alcohol is driven off. The

reaction mixture is then refluxed, for example for 2 to 6 hours, cooled and the solid phases separated and washed with toluene and dried.

EXAMPLE 1 showed major peaks at 1,300, 1,087, 800 and 765 reciprocal centimeters.

EXAMPLE 2 Biuret (0.10 mole) was suspended in 200 mls. of toluene and a solution of potassium hydroxide (0.10 mole) in 10 mls. of methanol was added to the suspension. The resulting mixture was distilled to remove the methanol and then refluxed for 8 hours. The solid phase was separated, washed with toluene and dried in vacuo at 70 C. It contained 30.3 percent by weight of the compound having the empirical formula KC N HO Infrared absorption spectra measurements showed strong peaks at 1,300, 1,087, 800 and 765 reciprocal centimeters.

What we claim is:

l. A process for making compositions possessing fire-extinguishing properties comprising heating biuret with an alkali selected from sodium hydroxide and potassium hydroxide under anhydrous conditions to a temp eratu re of at least 95 C.

2. A process as claimed in claim 1 111 which the alkali metal hydroxide and biuret are mixed in powdered form and heated under anhydrous conditions at 100 C. to 130 C.

3. A process as claimed in claim 1 in which the alkali metal hydroxide and biuret are heated together in an inert, nonaqueous, liquid organic reaction medium of sufficiently high boiling point to allow the reaction system to be heated or refluxed at temperatures above about 95 C. under atmospheric pressure.

a a: m 4- a 

2. A process as claimed in claim 1 in which the alkali metal hydroxide and biuret are mixed in powdered form and heated under anhydrous conditions at 100* C. to 130* C.
 3. A process as claimed in claim 1 in which the alkali metal hydroxide and biuret are heated together in an inert, nonaqueous, liquid organic reaction medium of sufficiently high boiling point to allow the reaction system to be heated or refluxed at temperatures above about 95* C. under atmospheric pressure. 